Changeset 263055 in webkit

Timestamp:

Jun 15, 2020, 12:59:24 PM (5 years ago)

Author:

mark.lam@apple.com

Message:

Do not install the VMTraps signal handler if Options::useJIT=false.
​https://bugs.webkit.org/show_bug.cgi?id=212543
<rdar://problem/63772519>

Reviewed by Keith Miller.

VMTraps is only needed for JITted code. Hence, if the JIT is disabled, we should
set Options::usePollingTraps() to true to indicate that we won't be using VMTraps.

With this change, we no longer install any signal handling machinery if
Options::useJIT() is false.

Because we may still disable the JIT even if useJIT() is true (due to failure to
allocate JIT memory or a number of other factors), we will also add a check of
VM::canUseJIT() in initializeThreading(), and disable useJIT() if needed. Of
course, this also means we need to call Options::recomputeDependentOptions() to
make other options consistent with useJIT() being false.

• runtime/InitializeThreading.cpp:

(JSC::initializeThreading):

• runtime/Options.cpp:

(JSC::disableAllJITOptions):
(JSC::Options::recomputeDependentOptions):
(JSC::recomputeDependentOptions): Deleted.

• runtime/Options.h:
• runtime/VMTraps.cpp:

(JSC::VMTraps::initializeSignals):

• tools/SigillCrashAnalyzer.cpp:

(JSC::SigillCrashAnalyzer::instance):

Location:

trunk/Source/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• runtime/InitializeThreading.cpp (modified) (1 diff)
• runtime/Options.cpp (modified) (4 diffs)
• runtime/Options.h (modified) (2 diffs)
• runtime/VMTraps.cpp (modified) (1 diff)
• tools/SigillCrashAnalyzer.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/ChangeLog

@@ +1 @@
+2020-06-15  Mark Lam  <mark.lam@apple.com>
+
+        Do not install the VMTraps signal handler if Options::useJIT=false.
+        https://bugs.webkit.org/show_bug.cgi?id=212543
+        <rdar://problem/63772519>
+
+        Reviewed by Keith Miller.
+
+        VMTraps is only needed for JITted code.  Hence, if the JIT is disabled, we should
+        set Options::usePollingTraps() to true to indicate that we won't be using VMTraps.
+
+        With this change, we no longer install any signal handling machinery if
+        Options::useJIT() is false.
+
+        Because we may still disable the JIT even if useJIT() is true (due to failure to
+        allocate JIT memory or a number of other factors), we will also add a check of
+        VM::canUseJIT() in initializeThreading(), and disable useJIT() if needed.  Of
+        course, this also means we need to call Options::recomputeDependentOptions() to
+        make other options consistent with useJIT() being false.
+
+        * runtime/InitializeThreading.cpp:
+        (JSC::initializeThreading):
+        * runtime/Options.cpp:
+        (JSC::disableAllJITOptions):
+        (JSC::Options::recomputeDependentOptions):
+        (JSC::recomputeDependentOptions): Deleted.
+        * runtime/Options.h:
+        * runtime/VMTraps.cpp:
+        (JSC::VMTraps::initializeSignals):
+        * tools/SigillCrashAnalyzer.cpp:
+        (JSC::SigillCrashAnalyzer::instance):
+
 2020-06-15  Keith Miller  <keith_miller@apple.com>
 

trunk/Source/JavaScriptCore/runtime/InitializeThreading.cpp

@@ -67 +67 @@
         ExecutableAllocator::initialize();
         VM::computeCanUseJIT();
+        if (!VM::canUseJIT()) {
+            Options::useJIT() = false;
+            Options::recomputeDependentOptions();
+        }
 
-        if (VM::canUseJIT() && Options::useSigillCrashAnalyzer())
+        if (Options::useSigillCrashAnalyzer())
             enableSigillCrashAnalyzer();
 

trunk/Source/JavaScriptCore/runtime/Options.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2011-2019 Apple Inc. All rights reserved.
+ * Copyright (C) 2011-2020 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -376 +376 @@
 }
 
-static void recomputeDependentOptions()
-{
-#if !defined(NDEBUG)
-    Options::validateDFGExceptionHandling() = true;
-#endif
-#if !ENABLE(JIT)
+static void disableAllJITOptions()
+{
     Options::useLLInt() = true;
     Options::useJIT() = false;
@@ -389 +385 @@
     Options::useDOMJIT() = false;
     Options::useRegExpJIT() = false;
+}
+
+void Options::recomputeDependentOptions()
+{
+#if !defined(NDEBUG)
+    Options::validateDFGExceptionHandling() = true;
+#endif
+#if !ENABLE(JIT)
+    disableAllJITOptions();
 #endif
 #if !ENABLE(CONCURRENT_JS)
@@ -408 +413 @@
 #endif
 
+    // At initialization time, we may decide that useJIT should be false for any
+    // number of reasons (including failing to allocate JIT memory), and therefore,
+    // will / should not be able to enable any JIT related services.
     if (!Options::useJIT()) {
+        disableAllJITOptions();
+        Options::useConcurrentJIT() = false;
         Options::useSigillCrashAnalyzer() = false;
         Options::useWebAssembly() = false;
+        Options::usePollingTraps() = true;
     }
 

trunk/Source/JavaScriptCore/runtime/Options.h

@@ -1 +1 @@
 /*
- * Copyright (C) 2011-2019 Apple Inc. All rights reserved.
+ * Copyright (C) 2011-2020 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -88 +88 @@
 
     JS_EXPORT_PRIVATE static void ensureOptionsAreCoherent();
+    static void recomputeDependentOptions();
 
 #define DECLARE_OPTION_ACCESSORS(type_, name_, defaultValue_, availability_, description_) \

trunk/Source/JavaScriptCore/runtime/VMTraps.cpp

@@ -298 +298 @@
 {
 #if ENABLE(SIGNAL_BASED_VM_TRAPS)
-    if (!Options::usePollingTraps())
+    if (!Options::usePollingTraps()) {
+        ASSERT(Options::useJIT());
         SignalSender::initializeSignals();
+    }
 #endif
 }

trunk/Source/JavaScriptCore/tools/SigillCrashAnalyzer.cpp

@@ -1 +1 @@
 /*
- * Copyright (C) 2017-2018 Apple Inc. All rights reserved.
+ * Copyright (C) 2017-2020 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -200 +200 @@
     static std::once_flag once;
     std::call_once(once, [] {
+        ASSERT(Options::useJIT());
         installCrashHandler();
         analyzer = new SigillCrashAnalyzer;